Salvages #28199 by @bensargotest-sys. Aligns Kanban docs with current
tool registration: dispatcher-spawned task workers get task tools,
profiles that explicitly enable the kanban toolset get orchestrator
routing tools (kanban_list, kanban_unblock). Corrects failure-limit
text to current default of 2. Hardens the e2e subprocess script to
resolve repo root and use the spawnable default assignee. Updates the
diagnostics severity fixture to assert error below the critical
threshold.
81584940fe